Pecking order when introducing new chicks

We have three hens about 32wks old as well as eight chicks that are almost 11wks. About two weeks ago, we put the chicks in the coop, secured in a brooder box so they were safe and the hens could see and hear them. When the hens are out in the yard, the chicks have the run of the coop. We don't have an outdoor run just yet, so the chicks don't get out much (they run like mad and are so hard to catch!).

The chicks are getting too big for the brooder box, and we think it's time to integrate them with the other three. The few times we've left them out in the coop with the older girls, they hide away on top of the box (or in the box) as the older ones will go after them. I realize there is a pecking order to be established between the lot, but how much is too much? The last thing we want is for it to get out of control while we're not around.

There is one hen in particular who is the lowest of the three hens, and she seems to be the one most determined to peck at the chicks. When we got the hens from the hatchery at 19wks, this particular hen had her beak trimmed quite low. I now think she was debeaked, perhaps for continuous pecking.

In addition to this, we have one chick who is lame. We're not quite sure what happened to her (though my DH suspect he may have hit her with something accidentally) but she limps and isn't growing as well as the others. She is a prime target for the older ones.

Is it safe to just take the box away and let things happen as they will?